This invention relates generally to the field of liquid droplet production, and in particular to the production of fine liquid droplets. More specifically, the invention relates to novel aerosol generators and manufacturing processes for producing such aerosol generators.
The ability to aerosolize or nebulize small liquid droplets is important to a variety of industries. Merely by way of example, many pharmaceuticals can now be delivered to the lungs in liquid form. Aerosolization is also a useful technique to dispense deodorizers, perfumes, insectizers or the like into the atmosphere.
One exemplary technology for producing fine liquid droplets is by supplying liquid to an aperture plate and vibrating the aperture plate to eject liquid droplets through the apertures. Such a technique is described generally in U.S. Pat. Nos. 5,164,740; 5,938,117; 5,586,550; 5,758,637 and 6,085,740, the complete disclosures of which are herein incorporated by reference.
This invention is related to manufacturing processes to produce aerosol generators utilizing such technology. The invention also relates to novel aerosol generators that may be manufactured in a low cost and/or high volume manner.
In one embodiment, a method is provided for producing an aerosol generator. The methods utilize a vibratable member having a plurality of apertures that are configured to produce liquid droplets when a liquid is applied to the vibratable member and the vibratable member is vibrated. According to the method, a support member is injected molded about the vibratable member, and a vibratable element is placed in vibrational communication with the vibratable member. In this way, an aerosol generator may be produced in a cost effective manner and in high volumes by injection molding the support element about the vibratable member.
In one aspect, the vibratable element and the vibratable member may be placed together in the mold before injection molding the support member. Alternatively, the vibratable element may be coupled to the support member after the injection molding process.
In some cases, a stiffening element may be placed between the vibratable element and the vibratable member to facilitate the transmission of vibrational energy from the vibratable element to the vibratable member. The stiffening element may be placed between the vibratable element and the vibratable member in a variety of ways. For example, the stiffening element may be placed into the mold along with the vibratable member. After injection molding the support member, the vibratable element may be coupled to the stiffening element. Alternatively, the vibratable element may be coupled to the stiffening element and then placed into the mold with the vibratable member where the support member is injection molded.
A variety of materials may be used to form the support member. Examples of materials that may be injection molded to form the support member include polystyrene, polysulfone, glass filled plastics, other plastics, and the like. In one particular aspect, the mold is configured to produce a support member that is cup shaped in geometry, although other shapes are possible, such as an annular ring. The vibratable member is placed into the mold such that an outer periphery of the vibratable member is surrounded by the support member, with a center portion of the vibratable member that has the apertures being free to receive and eject liquid. For example, a rear surface of the vibratable member that is within the cup may be supplied with liquid that is then ejected in the form of fine liquid droplets from the front surface upon actuation of the vibratable element.
In one configuration, the vibratable element may comprise an annular piezoelectric element that is disposed about the center portion of the vibratable member. The stiffening element may also be annular in geometry and be concentric with the piezoelectric element.
The invention further provides an aerosol generator that is constructed of a vibratable member having a front surface, a rear surface, an outer periphery and a central portion having a plurality of apertures. Preferably, the apertures taper from the rear surface to the front surface to permit fine liquid droplets to be produced through the apertures upon vibration. A support member is injection molded about the outer periphery such that the central portion is available to receive a liquid to be aerosolized. A vibratable element is in vibrational communication with the vibratable member to vibrate the vibratable member upon vibration of the vibratable element.
In one aspect, the vibratable element is an annular piezoelectric element that is coupled to the support member. Optionally a stiffening element, such as a rigid washer, may be placed between the piezoelectric element and the vibratable member. In another aspect, the support member may be constructed of a stiff material that is capable of being injection molded. In one particular aspect, the support member is injection molded into the shape of a cup, with the front surface of the vibratable member facing away from the cup.
In another embodiment, such an aerosol generator is placed within a housing to form an aerosolizer or nebulizer. The housing may conveniently include a mouthpiece so that aerosolized liquid may be delivered to a user""s airway. A power supply to supply power to the piezoelectric element, and a supply of liquid may also be disposed within the housing.